Device for the rapid freezing of substances

ABSTRACT

The invention relates to a device for the rapid freezing of the surface or for the complete freezing of starting substances, in particular of food or pharmaceuticals, said device comprising a treatment zone (B), through which a cryogenic liquefied gas flows as a coolant, said gas thereby freezing at least the surfaces of the starting substances and thereby causing relative movements between the starting substances, which are immersed in the coolant. The treatment zone (B) is made up of modules (M 1,  M 2,  M 3,  M 4 ) and the length thereof can be changed by adding or removing one or a plurality of modules.

The invention relates to a device for the rapid freezing of the surface or for the complete freezing of starting substances, in particular of food or pharmaceuticals, thereby freezing at least the surfaces of the starting substances and thereby causing relative movements between the starting substances.

The object of producing so-called IQF (Individual Quick Frozen) products, in which the frozen starting substances are available so as to be packaged in containers and being freely movable against one another, from starting substances by means of freezing occurs frequently in the food industry. When further processing IQF products, for example in the kitchen, they can be dosed simply and they make it possible to remove only a portion of the container content without having the defrost the entire content. If the starting substances are foods encompassing wet surfaces, such as prawns, berries or fungi, for example, it must be ensured that there is a relative movement of the starting substances to one another during the freezing, because the starting substances can otherwise easily freeze to one another and can form agglomerates. It is the state of the art to generate the relative movement by means of jogging units, in which the starting substances are frozen, or to fluidize them by means of a cold gas flow during the freezing process.

Devices are furthermore known, as they are described in patent specification EP0393078, among others, in which the starting substances are transported through a treatment zone in a turbulent or laminar flow of cryogenic liquefied gas. The starting substances are surrounded by cryogenic liquefied gas, which causes a rapid freezing of the surface and which thus prevents an adhesion of the starting substances. On the other hand, the desired relative movement between the starting substances is generated here at the surface of the starting substances by means of the turbulences in the liquefied gas flow and/or by means of a boiling liquid. At the end of the treatment zone, where the liquefied gas is separated from the starting substances, a product is available, which is possibly transformed into an IQF product by means of the subsequent treatment steps.

The freezing state, which can be attained in the treatment zone, depends on the type and the quantity of the used starting substances and on the time during which the coolant and the starting substances, which are to be frozen, are in contact (contact time). The device described in patent specification EP0393078 only offers few possibilities for the variation of the contact time, such as the changing of the coolant flow or the exchange of the coolant. The spectrum of the starting substances, which are treated by means of this device, is thus limited.

It is thus the object of the instant invention embodiments to specify a device of the afore-mentioned type, which makes it possible to vary the contact time in a simple manner and to thus adapt it to the requirements, which result from the characteristics of the starting substances, which are to be frozen, and from the demands on the product, which is produced by means of freezing.

The object is solved according to the invention in that the treatment zone is made up of modules and in that its length can be changed by adding or removing one or a plurality of modules.

The time during which the coolant and the starting substances, which are to be frozen, are in contact (contact time) can also be changed by means of the variability of the length of the treatment zone. Under otherwise the same conditions, the following applies: the longer the treatment zone, the longer the contact time. However, the contact time can only be changed in discrete steps by adding or removing one or a plurality of modules.

An advantageous embodiment of the device according to the invention thus provides for the inclination of at least one module to be preferably continuously adjustable as compared to the horizontal (inclination). The driving force for the movement of the coolant as well as of the starting substances, which are immersed in the coolant, through the treatment zone, is mainly the force of gravity and the grade resistance, respectively. An increase of the inclination of a module thus leads to an increase of this driving force and thus to a reduction of the contact time. If the treatment zone is made up of more than one module, the modules can encompass the same or different inclinations.

By means of a simultaneous change of the length of the treatment zone and of the inclination of one or a plurality of modules, the device according to the invention makes it possible for the contact time to change continuously in a broad range and to thus adapt it in a specific manner to the characteristics of the starting substances (type, quantity, temperature, water content) and to the demands made on the product, which is produced by means of freezing.

The device according to the invention furthermore allows for the use of different coolants, because different cooling characteristics of the coolants are compensable by changing the contact time. Provision is preferably made for liquid nitrogen or liquid oxygen or a mixture of liquid nitrogen and liquid oxygen as coolant.

So as to be able to also install a device according to the invention in small available spaces, such as they occur during the installation in existing cooling treatment devices (e.g. tunnel freezer), an advantageous embodiment of the invention provides for two modules, which succeed one another in flow direction of the coolant to be arranged for the most part underneath one another, wherein the inclinations of the two modules ensure that the flow directions in the two modules are substantially oriented in opposite direction.

Advantageously, the modules are embodied as straight pipes or as straight chamfers, wherein the pipes preferably encompass a rectangular cross section and the chamfers preferably encompass a U-shaped cross section.

The device according to the invention makes it possible to produce products comprising a defined quality from different starting substances. The configuration of a plurality of modules to be located on top of one another results in a compact design of a treatment zone, whereby it is possible to integrate such a device into existing freezers, such as, e.g., in tunnel freezers.

The invention will be defined in more detail below by means of an exemplary embodiment, which is schematically illustrated in the FIGURE. The exemplary embodiment is a portion of a device for producing an IQF product by means of rapid freezing of chunky starting substances in a liquid coolant. The directions of substance flows are indicated by means of arrows for clarification purposes.

The device is equipped with a feeding device Z for feeding a coolant, which is preferably a cryogenic liquid nitrogen, which is joined by the first module M1, which is embodied as a chamfer comprising a U-shaped cross section, of the treatment zone B. The coolant feed is thereby carried out in such a manner that the coolant comprising a profile, which is homogeneous across the entire flow cross section, enters into the first module M1. The starting substances, which are to be frozen, can be introduced into the device according to the invention via the loading point A and thus reach the flowing coolant, from where they are dragged along and thereby moved against one another.

Further modules M2 to M4, the inclinations of all of which can be changed as compared to the horizontal, are arranged underneath one another underneath the first module M1. The coolant and the starting substances, which are dragged along by the coolant, flow downward at the end of the modules M1, M2 and M3 and thus reach into the respective following module. The number of modules and the inclinations thereof are chosen in such a manner that the product at the end of the module M4 encompasses a defined degree of freezing, by means of which it falls onto the conveyor belt T, which is arranged underneath the treatment zone B and by means of which it can be fed to a further, non-illustrated cooling treatment after separation of the coolant. 

1. A device for the rapid freezing of the surface or for the complete freezing of starting substances, in particular food or pharmaceuticals, comprising a treatment zone through which a cryogenic liquefied gas flows as a coolant, said gas freezing at least surfaces of the starting substances and causing relative movements between the starting substances which are immersed in the coolant, the treatment zone comprising a plurality of modules to which can be added or removed one or a plurality of the modules for adjusting a length of the treatment zone, wherein at least one of the plurality of modules is inclined against the horizontal and is adjustable in its inclination with respect to the horizontal.
 2. (canceled)
 3. The device according to claim 1, wherein two modules of the plurality of modules which succeed one another in a flow direction of the coolant are substantially arranged underneath one another and inclinations of the two modules provide flow directions in the two modules to be substantially oriented in opposite directions.
 4. The device according to claim 1, wherein each one of the plurality of the modules comprise a straight pipe, the straight pipe comprising a rectangular cross section.
 5. The device according to claim 1, wherein each one of the plurality of the modules comprise a straight chamfer, the straight chamfer comprising a U-shaped cross section. 